The remaining and less typical subordinal groups - sometimes ranked as orders by themselves - include among living animals the Proboscidea, cr elephants, and the Hyracoidea, or hyraxes, and among extinct groups the Amblypoda, Ancylopoda, Barypoda, Condylarthra, Litopterna and Toxodontia.

Whether there is any relationship with the Hyracoidea cannot be determined until we are acquainted with the forerunners of Arsinoitherium, which is evidently a highly specialized type.

HYRACOIDEA, a suborder of ungulate mammals represented at the present day only by the Syrian hyrax (Procavia syriaca), the "coney" of the Bible, and its numerous African relatives, all of which may be included in the single genus Procavia (or Hyrax), and consequently in the family Procaviidae.

For many years extinct representatives of the Hyracoidea were unknown, partly owing to the fact that certain fossils were not recognized as really belonging to that group. The longest known of these was originally named Leptodon graecus, but, on account of the preoccupation of the generic title, the designation has been changed to Pliohyrax graecus.